The main purpose of this project is to provide more precise information concerning the temporal relationships pertaining to ovulation in the normal human menstrual cycle utilizing pelvic ultrasound and a rapid radioimmunoassay for LH combined with the assessment of two phenomena: (1) ovservation as to the occurrence or lack of occurence of ovulation and (2) the stage of oocyte maturation if ovulation has not occured. In (1) we will use pelvic ultrasound; the rapid LH assay to allow us to plan groups of laparoscopies which are time bracketed around expected ovulation. The presence or absence of ovulation in the time brackets will then be subjected to probit analysis to give us the median ovulation time in relation to the onset of the LH surge. In (2) we will use pelvic ultrasound and the rapid LH assay to plan laparoscopies in groups; time bracketed before ovulation. At laparoscopy the oocyte from the preovulatory follicle will be harvested and the stage of maturation will be determined. The mean temporal relationships of each stage of meiosis to the onset of the LH surge will be determined. These results will be compared with previously reported in-vitro studies of oocyte maturation and with other studies concerning oocyte maturation changes after hCG injection. Our proposed work in the natural cycle will either confirm or refute these previously reported studies. Earlier work has also related the stages of meiosis to ovulation, so that if our results are in congruence we will have additional data as to the time relationship between the onset of the LH surge and ovulation. We also plan to study the concentration of steroids in the antral fluid of the preovulatory follicle at various time intervals after the onset of the LH surge, so that we can delineate the change in hormone pattern associated with impending ovulation. Increased and more detailed knowledge concerning the exact timing of ovulation during the natural cycle could lead to imporvements in both the present method of contraception using the rhythm mehtod and be helpful in attempts to increase conception in infertile couples.